The present invention is generally directed to various methods of forming conductive through-wafer vias. In one illustrative embodiment, the method comprises providing a layer of semiconducting material, forming a layer of metal on a first side of the layer of semiconducting material, forming an opening in the layer of semiconducting material to thereby expose a portion of the layer of metal, the opening extending from at least a second side of the layer of semiconducting material to the layer of metal, and performing a deposition process to form a conductive contact in the opening using the exposed portion of the metal layer as a seed layer. In another illustrative embodiment, the method comprises providing a layer of semiconducting material, forming a first layer of insulating material on a first side of the layer of semiconducting material, forming a layer of metal on the first layer of insulating material, forming an opening in the layer of semiconducting material and the first layer of insulating material to thereby expose a portion of the layer of metal, the opening extending from at least a second side of the layer of semiconducting material to the layer of metal, and performing a deposition process to form a conductive contact in at least the opening using the exposed portion of the metal layer as a seed layer.
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1. A method, comprising:
providing a layer of semiconducting material;
forming a layer of metal on a first side of said layer of semiconducting material;
forming an opening in said layer of semiconducting material to thereby expose a portion of said layer of metal, said opening extending from at least a second side of said layer of semiconducting material to said layer of metal; and
performing a deposition process to form a conductive contact in said opening using said exposed portion of said metal layer as a seed layer.
15. A method, comprising:
providing a layer of silicon;
depositing a layer of metal on a first side of said layer of silicon;
forming an opening in said layer of silicon to thereby expose a portion of said layer of metal, said opening extending from at least a second side of said layer of silicon to said layer of metal;
forming a layer of insulating material on at least portions of said layer of silicon within said opening; and
performing a deposition process to form a conductive contact in said opening above said layer of insulating material using said exposed portion of said metal layer as a seed layer.
28. A method, comprising:
providing a layer of semiconducting material;
forming a first layer of insulating material on a first side of said layer of semiconducting material;
forming a layer of metal on said first layer of insulating material;
forming an opening in said layer of semiconducting material and said first layer of insulating material to thereby expose a portion of said layer of metal, said opening extending from at least a second side of said layer of semiconducting material to said layer of metal; and
performing a deposition process to form a conductive contact in at least said opening using said exposed portion of said metal layer as a seed layer.
42. A method, comprising:
providing a layer of silicon;
forming a first layer of insulating material on a first side of said layer of silicon;
forming a layer of metal on said first layer of insulating material;
forming an opening in said layer of silicon and said first layer of insulating material to thereby expose a portion of said layer of metal, said opening extending from at least a second side of said layer of silicon to said layer of metal;
forming a second layer of insulating material on at least portions of said layer of silicon within said opening; and
performing a deposition process to form a conductive contact in at least said opening above said second layer of insulating material using said exposed portion of said metal layer as a seed layer.
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1. Field of the Invention
This present invention is generally directed to the field of semiconductor manufacturing, and, more particularly, to various methods of forming conductive through-wafer vias.
2. Description of the Related Art
Integrated circuit technology relies on transistors to formulate vast arrays of functional circuits. The complexity of these circuits requires the use of an ever-increasing number of linked transistors. As the number of transistors increases, the integrated circuitry dimensions shrink. One challenge in the semiconductor industry is to develop improved methods for electrically connecting and packaging circuit devices which are fabricated on the same and on different wafers or chips. In general, it is desirable in the semiconductor industry to construct transistors which occupy less surface area on the silicon chip/die.
As integrated circuit technology progresses, there is a growing desire for a “system on a chip.” Ideally, a computing system would be fabricated with all the necessary integrated circuits on one wafer, as compared with today's method of fabricating many chips of different functions and packaging them to assemble a complete system. Such a structure would greatly improve integrated circuit performance and provide higher bandwidth. In practice, it is very difficult with today's technology to implement a truly high-performance “system on a chip” because of vastly different fabrication processes and different manufacturing yields for the logic and memory circuits. Thus, what is needed is an improved method and structure which continues to approach the ideal set-up of a “system on a chip” and thus improves the integration of different chips in an integrated circuit.
As a result, there are economic advantages associated with forming a module or system from an interconnected group of different types of previously-tested integrated circuits (i.e., known good die). Further advantages can result from mounting the different types of integrated circuits in die form on a common substrate and then encapsulating the composite assembly in a package common to all of the die to form a module, known as a multichip module or MCM. In MCMs, the die are interconnected to wiring formed on the common substrate, also known as an interposer, using conventional interconnection technology.
As the area of each die in an MCM increases, a mismatch between the thermal coefficient of expansion of the die and the interposer becomes increasingly critical, at least in part because the thickness of the material forming the die is not increased as the area of the die is increased. One solution to this problem is to make the interposer from the same material that the die are made from, e.g., silicon. This allows increasingly complex integrated circuits to be interconnected without exaggerating thermal coefficient of expansion mismatch problems that could occur either during packaging or as a result of thermal cycling in normal use. Additionally, passive components may be formed or mounted on the interposer.
One illustrative prior art technique for forming such through-hole contacts will now be described with reference to
The next process involves the formation of a seed layer 24, e.g., a copper seed layer. The copper seed layer 24 may be conformally formed on the substrate 20 and in the openings 22. The copper seed layer 24 may have a thickness of approximately 20-100 nm, and it may be formed by, for example, a physical vapor deposition (PVD) process or a chemical vapor deposition (CVD) process. Thereafter, an electrical (electroplating) or chemical (electroless) process may be performed to deposit the bulk copper layer 26 above the substrate 20 and in the openings 22, as indicated in FIG. 2C. Then, one or more chemical mechanical polishing (CMP) operations are performed to remove the excess bulk copper layer 26, thereby leaving the through-hole contacts 25 in the openings 22, as shown in FIG. 2D. Additional processing operations may be performed to couple one or more integrated circuit devices, e.g., memory devices, logic devices, etc., to the desired contacts 25.
The above-referenced process flow may be problematic in many respects for future technologies. For example, the aspect ratio of the openings 22 will tend to increase in future generation products. As a result, the conformal deposition of the copper seed layer 24 may be more difficult to achieve. Such difficulties may lead to the formation of voids in the contacts 25, all of which will reduce the efficiency of the contacts 25.
The present invention is directed to a method that may solve, or at least reduce, some or all of the aforementioned problems.
The present invention is generally directed to various methods of forming conductive through-wafer vias. In one illustrative embodiment, the method comprises providing a layer of semiconducting material, forming a layer of metal on a first side of the layer of semiconducting material, forming an opening in the layer of semiconducting material to thereby expose a portion of the layer of metal, the opening extending from at least a second side of the layer of semiconducting material to the layer of metal, and performing a deposition process to form a conductive contact in the opening using the exposed portion of the metal layer as a seed layer.
In another illustrative embodiment, the method comprises providing a layer of semiconducting material, forming a first layer of insulating material on a first side of the layer of semiconducting material, forming a layer of metal on the first layer of insulating material, forming an opening in the layer of semiconducting material and the first layer of insulating material to thereby expose a portion of the layer of metal, the opening extending from at least a second side of the layer of semiconducting material to the layer of metal, and performing a deposition process to form a conductive contact in at least the opening using the exposed portion of the metal layer as a seed layer.
The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
The present invention will now be described with reference to the attached figures. Although various regions and structures shown in the drawings are depicted as having very precise, sharp configurations and profiles, those skilled in the art recognize that, in reality, these regions and structures are not as precise as indicated in the drawings. Additionally, the relative sizes of the various features and doped regions depicted in the drawings may be exaggerated or reduced as compared to the size of those features or regions on fabricated devices. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present invention. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.
The metal layer 32 may be comprised of a variety of materials, such as copper, platinum, aluminum, tantalum/copper (bi-layer), and it may have a thickness 35 that ranges from approximately 150-250 nm (1500-2500 Å). In fact, for reasons that will be understood after a complete reading of the present application, in some embodiments, the metal layer 32 may be made as thin as possible while still accomplishing its intended function. The metal layer 32 may be formed using a variety of processes, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD), electroplating or electroless processes, etc. Depending upon the material selected for the metal layer 32, a separate seed layer (not shown), such as a copper seed layer, may be formed on the surface 31 of the substrate 30 prior to the formation of the metal layer 32.
Next, as shown in
The openings 34 may be formed by a variety of techniques, such as, for example, a laser process, a dry etch process, a photoelectrochemical process, etc., or a combination of these processes. Depending upon the particular process flow selected, the metal layer 32 may act as an etch stop layer. After the openings 34 are formed, a cleaning process may be performed to remove residual materials from the openings 34. The material used for the metal layer 32 should be selected such that it is compatible with the cleaning materials and processes used to form and clean the openings 34.
As mentioned above, a combination of processes may be used to form the openings 34. For example, in one illustrative embodiment, a laser process may be performed to remove the bulk of the substrate material within the openings 34, i.e., approximately 70-80% of the substrate material may be removed using a laser process. Thereafter, a dry etch process, with a removal rate on the order of approximately 2-3 μm/min, or a photoelectrochemical etch process, with a removal rate on the order of approximately 1-2 μm/min may be used to remove the remaining substrate material.
The next operation involves the formation of a layer of insulating material 38 in the openings 34 and on the surface 39 of the substrate 30, as shown in FIG. 3C. The layer of insulating material 38 may be comprised of a variety of materials, and it may be formed by a variety of techniques. For example, the layer of insulating material 38 may be comprised of silicon dioxide or paralene. In one particularly illustrative embodiment, the layer of insulating material 38 may be comprised of a thermally grown layer of silicon dioxide having a thickness that ranges from approximately 100-500 nm.
The next step involves forming a conductive metal contact 42 (see
Next, as shown in
The next process involves the formation of the layer of insulating material 38A on the surface 39 of the substrate 30 and in the openings 34, as shown in FIG. 4C. An electroplating process or an electroless process may then be used to form the conductive contacts 42, as indicated in FIG. 4D. After this process is completed, the portions of the metal layer 32 positioned outside of the openings 34 are removed by performing one or more chemical mechanical polishing operations. Thereafter, traditional operations may be performed as desired. For example, the excess portions of the metal layer 32 may be removed down to the surface 45 of the layer of insulating material 38 by performing one or more CMP processes. Alternatively, the thickness of the metal layer 32 may be reduced and left in place. The thinned metal layer 32 may then be patterned to define the necessary wiring lines for the various devices coupled to the substrate 30.
The present invention is generally directed to various methods of forming conductive through-wafer vias. In one illustrative embodiment, the method comprises providing a layer of semiconducting material, forming a layer of metal on a first side of the layer of semiconducting material, forming an opening in the layer of semiconducting material to thereby expose a portion of the layer of metal, the opening extending from at least a second side of the layer of semiconducting material to the layer of metal, and performing a deposition process to form a conductive contact in the opening using the exposed portion of the metal layer as a seed layer. In further embodiments, the layer of semiconducting material may be comprised of silicon, and the layer of metal may be comprised of copper, nickel or platinum.
In another illustrative embodiment, the method comprises providing a layer of semiconducting material, forming a first layer of insulating material on a first side of the layer of semiconducting material, forming a layer of metal on the first layer of insulating material, forming an opening in the layer of semiconducting material and the first layer of insulating material to thereby expose a portion of the layer of metal, the opening extending from at least a second side of the layer of semiconducting material to the layer of metal, and performing a deposition process to form a conductive contact in at least the opening using the exposed portion of the metal layer as a seed layer.
It should be understood from the foregoing that the present invention is not limited to silicon interposer applications. Rather, the present invention may be employed in a variety of other contexts, such as contact boards, flip chips and stacked chips.
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.
Patent | Priority | Assignee | Title |
10010977, | May 05 2004 | Micron Technology, Inc. | Systems and methods for forming apertures in microfeature workpieces |
11177175, | Dec 10 2003 | Micron Technology, Inc. | Microelectronic devices and methods for filling vias in microelectronic devices |
11476160, | Sep 01 2005 | Micron Technology, Inc. | Microfeature workpieces and methods for forming interconnects in microfeature workpieces |
7179738, | Jun 17 2004 | Texas Instruments Incorporated | Semiconductor assembly having substrate with electroplated contact pads |
7411303, | Nov 09 2004 | Texas Instruments Incorporated | Semiconductor assembly having substrate with electroplated contact pads |
7413979, | Nov 13 2003 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for forming vias in microelectronic devices, and methods for packaging microelectronic devices |
7425499, | Aug 24 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for forming interconnects in vias and microelectronic workpieces including such interconnects |
7435913, | Aug 27 2004 | Micron Technology, Inc. | Slanted vias for electrical circuits on circuit boards and other substrates |
7531453, | Jun 29 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microelectronic devices and methods for forming interconnects in microelectronic devices |
7589008, | Dec 30 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for forming interconnects in microelectronic workpieces and microelectronic workpieces formed using such methods |
7622377, | Sep 01 2005 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpiece substrates having through-substrate vias, and associated methods of formation |
7629249, | Aug 28 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpieces having conductive interconnect structures formed by chemically reactive processes, and associated systems and methods |
7683458, | Sep 02 2004 | Round Rock Research, LLC | Through-wafer interconnects for photoimager and memory wafers |
7701064, | Oct 31 2007 | International Business Machines Corporation | Apparatus for improved power distribution in a three dimensional vertical integrated circuit |
7727887, | Oct 30 2007 | International Business Machines Corporation | Method for improved power distribution in a three dimensional vertical integrated circuit |
7749899, | Jun 01 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microelectronic workpieces and methods and systems for forming interconnects in microelectronic workpieces |
7750477, | Oct 09 2002 | Round Rock Research, LLC | Through-hole contacts in a semiconductor device |
7759800, | Nov 13 2003 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microelectronics devices, having vias, and packaged microelectronic devices having vias |
7795134, | Jun 28 2005 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Conductive interconnect structures and formation methods using supercritical fluids |
7829976, | Jun 29 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microelectronic devices and methods for forming interconnects in microelectronic devices |
7830018, | Aug 31 2007 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Partitioned through-layer via and associated systems and methods |
7863187, | Sep 01 2005 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpieces and methods for forming interconnects in microfeature workpieces |
7884015, | Dec 06 2007 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for forming interconnects in microelectronic workpieces and microelectronic workpieces formed using such methods |
7892972, | Feb 03 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for fabricating and filling conductive vias and conductive vias so formed |
7902643, | Aug 31 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpieces having interconnects and conductive backplanes, and associated systems and methods |
7915736, | Sep 01 2005 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpieces and methods for forming interconnects in microfeature workpieces |
7956443, | Sep 02 2004 | Round Rock Research, LLC | Through-wafer interconnects for photoimager and memory wafers |
7973411, | Aug 28 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpieces having conductive interconnect structures formed by chemically reactive processes, and associated systems and methods |
8008192, | Jun 28 2005 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Conductive interconnect structures and formation methods using supercritical fluids |
8018069, | Oct 09 2002 | Round Rock Research, LLC | Through-hole contacts in a semiconductor device |
8084866, | Dec 10 2003 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microelectronic devices and methods for filling vias in microelectronic devices |
8105940, | Oct 30 2007 | International Business Machines Corporation | Power distribution in a vertically integrated circuit |
8247907, | Dec 06 2007 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for forming interconnects in microelectronic workpieces and microelectronic workpieces formed using such methods |
8294273, | Feb 03 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for fabricating and filling conductive vias and conductive vias so formed |
8322031, | Aug 27 2004 | Micron Technology, Inc. | Method of manufacturing an interposer |
8324100, | Feb 03 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods of forming conductive vias |
8367538, | Aug 31 2007 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Partitioned through-layer via and associated systems and methods |
8502353, | Sep 02 2004 | Round Rock Research, LLC | Through-wafer interconnects for photoimager and memory wafers |
8536046, | Aug 31 2007 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Partitioned through-layer via and associated systems and methods |
8536485, | May 05 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Systems and methods for forming apertures in microfeature workpieces |
8610279, | Aug 28 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpieces having conductive interconnect structures formed by chemically reactive processes, and associated systems and methods |
8664562, | May 05 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Systems and methods for forming apertures in microfeature workpieces |
8669179, | Sep 02 2004 | Round Rock Research, LLC | Through-wafer interconnects for photoimager and memory wafers |
8686313, | May 05 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | System and methods for forming apertures in microfeature workpieces |
8748311, | Dec 10 2003 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microelectronic devices and methods for filing vias in microelectronic devices |
8993354, | Sep 14 2012 | Kabushiki Kaisha Toshiba | Evaluation pattern, method for manufacturing semiconductor device, and semiconductor wafer |
9099539, | Aug 31 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpieces having interconnects and conductive backplanes, and associated systems and methods |
9214391, | Dec 30 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for forming interconnects in microelectronic workpieces and microelectronic workpieces formed using such methods |
9281241, | Dec 06 2007 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Methods for forming interconnects in microelectronic workpieces and microelectronic workpieces formed using such methods |
9293367, | Jun 28 2005 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Conductive interconnect structures and formation methods using supercritical fluids |
9452492, | May 05 2004 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Systems and methods for forming apertures in microfeature workpieces |
9570350, | Aug 31 2006 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microfeature workpieces having interconnects and conductive backplanes, and associated systems and methods |
9653420, | Dec 10 2003 | U S BANK NATIONAL ASSOCIATION, AS COLLATERAL AGENT | Microelectronic devices and methods for filling vias in microelectronic devices |
Patent | Priority | Assignee | Title |
5024966, | Dec 21 1988 | AT&T Bell Laboratories | Method of forming a silicon-based semiconductor optical device mount |
5998292, | Nov 12 1997 | GLOBALFOUNDRIES Inc | Method for making three dimensional circuit integration |
6359328, | Dec 31 1998 | Intel Corporation | Methods for making interconnects and diffusion barriers in integrated circuits |
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